Reduction of dye absorption in hardened gelatin relief matrices



Jan. 27, 1959 R. J. GoLDBr-:RG ET AL 2,870,704

REDUCTION oE DYE ABsoRPTIoN 1N HAEDENED GELATIN RELIEF MATRIcEs I Filed oct. e, 1957 WARM waff@ fc/f United States Patent i REDUCTION OF DYE ABSORPTION 1N HARD- ENED GELATIN RELIEF MATRICES Richard J. Goldberg, y=vl\lorth'lHollywood, and Earl M. Olds, Jr., Van Nuys, Calif., assignors to Technicolor Corporation, Hollywood, Calif., a corporation of Maine Application October 8, 1957, Serial N o. 688,921 6 Claims. (Cl. lill-149.1)l

One Well-known method of making photographs is to make a relief image in gelatin of the scene. The relief can be formed, for example, by exposing a silver containing gelatin layer through Ia transparent support, developing the image adjacent the support with a developer which hardens the gelatin coextensively with the de-v Relief matrices are normally made so that the result- I ing gelatin relief absorbs more dye than needed to transfer the color aspect of the scene to be reproduced. This is corrected by subjecting the saturated relief to a controlled water wash to removethe dye in excess of the amount desired. This operation is called washback and apparatus suitable for this purpose is disclosed in U. S. Patent No. 2,602,387.

Occasionally relief matrices are produced which absorb more excess dye vthan this subsequent washback operation can correct, especially where such matrices exceed the design limits yof machines designed for the purpose. Additionally, some matrices, initially satisfactory, become too absorbent on repeated reuse in making a series of imbibition prints. Such yoverly-absorbent or overscale relief matrices have heretofore been discarded.

The principal object `of-this invention is to provide a method of reducing the dye absorption, Without destroying the contrast, of a hardened gelatin relief matrix which absorbs dye in excess of the amount whichcan be corrected by the washback step in the transfer process.

In accordance with Ythis invention, themethod comprises the steps of treating lan overscale matrix with a proteolyticV enzyme bath for a predetermined time sufficient to solubilize only a portion lof the gelatin and dissolving this portion with a solvent, preferably warm water. By this method the dye absorption is reduced by the desired amount without destroying the contrast of the relief. Preferably the 'enzyme bath has a temperature of about ,70 to 80 F. a pH betweenabout 4 and l1, and the warm water has a temperature -of `about 120 to 140 F. The amount of excess absorbencyof amatrix, and hence the extent of the enzyme treatment required, is determined in conventional manner, for Yexample by making density measurements of a print made from the matrix land comparing with density standardsy of the scene. i j v A specific embodiment of this invention is in the accompanying drawing in .which i Fig. 1 is a flow chart;

Fig. 2 is a plot of the density characteristic curve of a magenta matrix before and after treatment; and

' Fig. 3 is a plot showing the relation between the time of enzyme treatment-in a standard enzyme bath and the reduction` inmatrix washback required.

illustrated "ice Referring to Fig. 1, overscale and overly-absorbent relief matrices are restored to the proper range -or 'degree of dye absorbency by treatment with a proteolytic enzyme bath A for a time sufficient to solubilize enough gelatin to reduce the matrix absorbency a predetermined amount, etching B with warm water to dissolve the solubilized gelatin, and drying C the etched relief. By this method the dye absorption of an overly-absorbent matrix is reduced to the desired range without destroying the contrast of the relief. The preservation of contrast is illustrated by the density curves shown in Fig. 2, curve 1 being the curve of a magenta matrix before treatment while curve 2 is the characteristic of the same matrix after treatment.

The amount of gelatin hydrolyzed and removed from the matrix and the resulting reduction in dye absorption is dependent on the concentration and temperature of the enzyme'solution and on the time of treatment.l The catalytic activity of each enzyme is usually at a maximum at a temperature not greatly above room temperature. An increase in temperature brings about an increase in the rate of reaction but also causes a loss in enzyme action. At temperatures above 120 F. loss in enzyme action becomes very rapid. Enzyme activity is lowered as the temperature is lowered below room temperature. Thus the preferred solution temperature is F. i5". The pH of enzyme solutions is usually around 7.0 but is generally not critical between the limits of about 4 and 1l. Beyond these limits there is a rapid loss in activity. Ata fixed temperature, solution activity is directly proportional to enzyme concentration and activity. While other activities 'could be used, solutions having enzyme` activity equivalent to about .002 gram of pure crystalline trypsin perl liter-of water have been found y suitable for the present invention.r

The amount of excess absorbency and hence the length of enzyme treatment required isfdetermined by conventional means. One method irs to make a density standard of the-Sceneor scenes as they are photographed and to compare Vthe density of a print made from the matrix with this standard. These density differences are correlatedv with the time in seconds lof immersion of the matrix in a given enzyme bath necessary to bring the density measurements'into satisfactory agreement, that is, into such agreement that the-nal adjustments can be made lin the washback step in the transfer'process.

Conveniently in theusual transfer process, the density differences are first correlated with the seconds of treatment in a given washback apparatus and then the seconds of immersion in a given enzyme bath are correlated with the reduction inj required washback thereby obtained. Then when more washback is required than the apparatus `can provide, the requirement is reduced lby treatment for vthe correlated time in a standardized enzyme bath. Fig, 3 illustrates the reduction'in required'washbackinjseconds `with various immersion times in an enzyme solution containing 4.5 grams Amprozyme 200 (activity equivalent to .002 g./.l. pure crystalline trypsin) perliter in water v at 75 i5, Y curve 3 representing yellow and magenta matrices and curve 4 representing cyan dyed matrices. v

While it is more convenient and hence preferred to vary the time of immersion in a solution of xed activ-ity to vcorrect matrices of varying amounts of over-absorbency, the same result can be achieved by using a standard time and varying theconcentration of enzyme or by a combination of both.

The enzymes useful `for this invention areproteolytic enzymes or any mixture ofenzymes containing la proteolytic enzyme. y Examples'r are trypsin, Amprozyme 200,-'

aerox/04 The yactionl ofthe enzymef isttoaenhance rthe'lhydrolysis of the protein'structure by vcatalyticaction, .the hydrolyzed `gelatin vthen #being' dissolved with` warm water.

This catalytic action ofthe enzyme-proceeds `without regard -to the presence or absence of metallic silver in the gelatin.

` Many vof -the ff commercial enzymes-.particularly those which -are mixtures yof enzymes, have lactivities which vary from sampleto sample. Theproper-concentration can be selected lby comparison withwthedesired@.concentration of pure trypsin -which has a substantially const-ant activity 'or lbyfpreparing a Vsolution `withlthe new sample and then increasing or decreasing -t-heaenzyme corlcentrat-ion'.to -bringfit finto agreement with a desiredl curve as illustrated in f-Fig. The Y method vvpresently used comprises Ameasuring -the idensity loss of va standard test-film withwa densitometer,:for-.example the Erpi 'densitometen in abath-ofa-desired lactivity for a lstandard immersion time,forexample L100 Vseconds. t

For reproducible results, 'this thenfbecomes the lstandard for comparison. Onanew ybatch ofenzyme, test-solutions of various concentrations are madeI andthe density losses on 'the samevtestlm are fplotted against concentration to determine the concentration -whichvgivesthe desired loss `at'the same conditions. `Each vnewV` solution made is tested to assure that--it.gives ythedesilfed loss, water or .enzyme being addedfifmece'ssary.

TheY enzymetreated relief'fmatrixisffed finto a 'warm water bath, preferably a cascade, to Vremove-.the retained enzyme solutionfand-the hydrolyzed gelatin. The ,fpreferred temperature -for this etch is'130 F.l 10. .fAt 150 F. the unhydrolyzed gelatin-willbegin to dissolve while att-90 `Efthe .solutiontimeis unduly long. .-On removal from this etching or'v waterbath, the relief-is given a rinse .in water attire-:same temperature Vandthe relief is then dried,A either -by-allowing evaporation lfat room temperature or-by.forced=drying. "While-the `water rinse has beenfound desirableto yavoid streaking,.it-can beomitted, especially-where solutionmake-up water :is allowed to -contact'fthe 'emergingllm. Y-'I'he.matrix;can then be dyed A- and used'ixra conventional'mannen By this method over-scale ymatrices can V-befreclaimed .and used rather than-discarded as heretofore.

This invention may be better understood by-reference to the following'specifc examples:

lEXAMPLE "NO. r1

A matrix representing the yellow aspect-.of a scene was tested and found to be over-scale by about .12 seconds more washback .treatment vthan could '.be provided by the washback step inthe transfer process. vThis matrix was treated as follows:

(1) Bathe for two minutes Ya`t75" F. ina water`solution (pH 7.0) "containing.002.gramrperliter of=pure crystalline trypsin,

(2) Etch 'in'water at 1'30F. for one minute, and

(3) Dry.

By this treatment the absorbency ofthe vmatrix was substantially reduced, without adversely affecting its contrast, to an amount readily corrected'in the conventional washback step.

EXAMPLE -NO. 2

zyme No. 200, anenzymem'ixtureof bacterial origin sold byJacque"Wolfe'f&"Co.,

(12) tEtch in waterlat FBOF.:for-oneeminutegand (3) Dry.

ST4 EXAMPLE NO. 3

A second matrix representing the cyan aspect of a scene was tested and found to be over-scale by about 16 seconds. This matrix was treated as follows:

(1) Bathe by immersion .ffm-L97 seconds at 75 F. in a water..solution .(.pH 7.0)y containing .002 `gram ,per liter trypsin,

(2) Etch in water at 130 F. for one minute,

l1EXAMPLELNG. l"4

The matrix -Iof Example 3 :was I'tr'eated as lfollows:

(1) Bathe by immersion for 97 seconds at 75 F. in a water solution (pH 7.0) containing V1.0 gram per liter of Rhozyme PF, an enzyme sold by Rohmand Hass Co.,

`(2) `Etch "in water at"130 FL for 'one.minute,

'1(4) Dry.

:Any convenient-'backing'canbe used 'such as glass, Celluloid/plastics,Letc. In each of the examples given, thegelatin was/supported on 'acetate film. The process also loperates 'irrespective ofthe .dyes used. `However conventional mageta yellowan`d vcyan dyes used to dyeglatin-'reliefs shouldbe employed. Examples of such dyesare as .f ollows:

i tY'ellow Chlorazol Brilliant Yellow 3G :(ICI) CII." 1 Direct Yellow'4 'grams '2100 Chlora'zol'fFast Orange "ER vv(ICI),"'C. I."Direct Orange`37 *'n A 0.25 Acetic acid,"g'lacial ;.mls V10.00 Water to" 'make 1200 liter Magenta Chlorazol Fast Pink BK (ICI), "C: I..'Direct`*Red `75. grams 3.60 Durazol Red l2B "'(ICI), "C. I. Direct Red :s1 l 'do l0.45 A'manil .BrilliantViolet'Rj CAAP), 'C. I.-."Direct '-vio1er3'0 ;do 0.50 'Acetic acid, glacial mls 50.00 Water `to make 1.00 I'liter Cyan Disulphine vGreen B '.(ICI),l yC."I. 'Acid "Green "9 y grams-- 0.25 Solway v'Celestol B 1(ICI), C. VI. Acid "Blue y 27 do 1.25 Lissamin'e :Green BN (ICI),"'.C. I. r'Acid Green 50 Y an 50.40 Acetic acidglacial. ;mls 30`.'00

water 'torniake y1.00 liter '1 Colon-Indexf:second edition 11956,1The American Society of Te'XtiI'eChenists and Cloursts.

Itshould -beun'destood that lthis .disclosure is 4for the Ipurpose `of illustration .only andnthat this invention includes. allequivalents and "modiications nfalling within the scopeof 'the .appended claims.

lWe'claim:

1. T'For reducingthe "dyeabso'rption `of"a hardenedY gelatin relief matrix ,which absorbsv dye in excess Yrif 'the amount'ne'cessary 'correctly '.to reproduce 'a 'coloraspect `o`f a "scene, 'the'method which comprises' vtreating the matrix witha .proteolytic enzyme bath. fora predetermined time slncient' to"sol bilize only a 4portion ofthe gelatin `and dissolving saidgelatin eportion with Vfafsolvent, *there by reducingthe dye absorptionewfithout*destroying the contrast.

2. For redufcingthedye absorption o'ahard'e'ned vgela'- tinlrelief `matrix which? bsorbsfdye JiniY excess of the amount necessary rcorrectlyto Trproducef a colorfaspect of a scene, th? ,Itiliatllod'fwhichicomprisesltreatingithesnla` trix with a proteolytic enzyme bath for a predetermined time suicient to solubilize only a portion of the gelatin and dissolving said gelatin portion in warm water, thereby reducing the dye absorption without destroying the contrast.

3. Method according to claim 2, wherein the enzyme bath has a temperature of approximately 75 F.

4. Method according to claim 2, wherein the warm water bath has a temperature of approximately 130 F.

5. Method according to claim 2, wherein the enzyme bath has a pH between about 4 and 11.

6. The method of reducing the dye absorption without destroying the contrast of a hardened gelatin relief matrix which absorbs dye in excess of the amount necessary to correctly reproduce a color aspect of a scene, comprising the steps of determining by density measurements the amount of excess absorbency of a matrix, treating said matrix in a proteolytic enzyme bath for a time suicient to solubilize that portion of the gelatin necessary to eliminate the excess absorbency beyond that normally corrected by washback, and dissolving said portion in warm 10 Water.

No references cited. 

1. FOR REDUCING THE DYE ABSORPTION OF A HARDENED GELATIN RELIEF MATRIX WHICH ABSORBS DYE IN EXCESS OF THE AMOUNT NECESSARY CORRECTLY TO REPRODUCE A COLOR ASPECT OF A SCENE, THE METHOD WHICH COMPRISES TREATING THE MATRIX WITH A PROTEOLYTIC ENZYME BATH FOR A PREDETERMINED TIME SUFFICIENT TO SOLUBILIZE ONLY A PORTION OF THE GELATIN AND DISSOLVING SAID GELATIN PORTION WITH A SOLVENT, THEREBY REDUCING THE DYE ABSORPTION WITHOUT DESTROYING THE CONTRAST. 